This invention relates to a three-point hitch, and more particularly to a contoured sliding block and bar bracket arrangement which can be set in a non-sway position to maintain a constant dimension between the draft arms while the hitch is either being lowered or raised, or it can be set in a sway position to permit limited lateral movement of draft arms.
A three-point hitch including two lower draft arms and an upper link is a conventional connection between a tractor and implement. A certain amount of lateral sway of the three-point hitch is tolerable and desirable in certain types of tractor mounted implements, such as moldboard plows, but for other implements, such as cultivators, the lateral movement of the implement relative to the tractor must be restricted or the implement may dig out parts of the crop rows being tilled.
Hitch sway limiting devices are known, and they usually consist of control members associated with the draft arms for limiting the lateral swaying of the three-point hitch throughout its vertical movement or only in the raised tractor travel position. Some prior art sway limitors consist of reversible sway blocks permitting sway of the hitch in the operating position and eliminating sway in the lift position of the hitch as exemplified by the U.S. Pat. Nos. 4,116,458 and 3,847,228. Other prior art sway control devices are adjustable or removable, for controlling the side sway of the draft links. Examples of other prior art sway limiting controls are found in U.S. Pat. Nos. 3,047,076, 3,627,060, 3,888,316 and 3,910,355. These prior art sway blocks of different sizes and configurations are either expensive or difficult and time-consuming to adjust or replace.
Another problem associated with the prior art constructions discussed is that there is no convenient way of adjusting from sway to non-sway, adjusting for wear of the sliding members, or for centering the implement behind the tractor. Adjustments are typically made by using additional parts such as shims or removing and changing parts. Thus, there has been a need for a simple sway limiting device which overcomes the disadvantages of the conventional sway control constructions.
A further problem with controlling the sway of many three-point hitches is that the draft arms do not move along a vertical line when being raised or lowered. That is, the draft arms are raised and lowered by lift links which are pivotally connected to the draft arms at one of their ends and which are pivotally connected to the tractor frame at their other ends. The lift links are angled such that they converge slightly at the ends pivotally connected to the tractor frame. Thus, the lift links are not perpendicular to the draft arms, and as the draft arms are raised and lowered, the movement of the draft arms is slightly arcuate rather than being along a straight line. There has been a need for a sliding sway control member which compensates for the arcuate movement of the draft arms to maintain a constant dimension between the draft arms in a non-sway setting as the draft arms are raised and lowered.